Improvement in heating and preparing stone for pavements



WL. meen.

Patented 01st. 17,1871.

UNITED STATES EErE.

cAMrEELL ALLEN, oE ALBANY, NEW vonk.

Speciiication forming part of Letters Patent No. 120,016, dated October 17, 1871.

To all whom it may concern.-

Be it known that l, CAMPBELL ALLEN, of Albany, in the county of Albany and State of New York, have invented a new and useful Improvement in Heating Gravel, Ste.; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the accompanying drawing forming part of this specification.

rEhis invention relates to a new and useful method of heating and drying broken stone or gravel for laying pavements, sidewalks, roadways, or for rooiing or other purposes.

The stone or gravel to be heated is placed in a steam-tight retort of strength and construction suitable to withstand the steam-pressure attending the degree of heat needed in the process. The door or head through which the retort has been charged being securely and tightly closed, steam of the requisite heat and pressure is let in. through a pipe directly among the stone or gravel to be dried and heated. The steam eX- pels the air through a cock at the bottom of the retort, which cock is left open for the pm'pose until the air and a portion of the condensed water has escaped. rlhis escape-cock then being closed, and the action of the steam continuing, the mass in the retort soon becomes heated to the temperature, or nearly to it, of the boiler from which the steam is derived. When this point has been reached, communication with the boiler is cut oft', a cock in the retort is opened, and the steam from the latter allowed to escape. The heat in the mass of material will, ii' suflicient, convert at atmospheric pressure all the condensed water therein immediately into steam, leaving the mass dry and hot. The mass in the retort must be raised sufticiently above 2120, so that the temperature above that point is suiiicient to convert all the condensed water in the mass into steam 5 otherwise the mass would be discharged at 2120, but leaving the stone wet. But the amount of heat contained in the condensed water thus converted into steam is very considerable, and to save this l convey the steam into another retort charged with material like the iirst. The steam rushing in among the material in the second retort imparts its heat thereto, and is condensed thereby, thus saving the heat.

-Figure lis a perspective view of one arrangement of apparatus, such as 1 contemplate using for carrying out my invention. Fig. 2 is a side elevation. Fig. 3 is a detail showin g part of the pipe. Fig. 4 is a plan view ot' another arrangement of the apparatus, and Fig. 5 is a transverse section of Fig. 4.

Similar letters of reference indicate corresponding parts.

.l propose to employ steam by a direct application of it to the broken stone or gravel to be heated, because of its capacity when applied under pressure to circulate quickly throughout all the spaces and crevices between the particles of broken stone or gravel, and at once convey the heat thereto, so as to applyit to the whole mass at once with but little ot' the loss which is incurred by the escape ofthe heat from the surface while penetrating to the interior, when applied as in the common way to the exterior of the vessel containing the gravel.

Another object attained by using' steam for heating the gravel is the facility with which the heat, or that part of it remaining in one vessel after the work is accomplished, greater than that required for the gravel when used, may be transferred to another vessel containing gravel to be heated, and in exhausting from the retort in which it is confined with the heated gravel to the one containing cold gravel or stone to be heated, thus converting all the water in the retort into steam instantly, which, escaping, will leave the gravel or stone, hot and dry, 'lit i'or use. I propose, therefore, to employ two or more, (preferring three,) cylindrical heaters or retorts, A B C, having openings D E at the ends or other parts, as may be preferred, for iilling and discharging, land doors or other means for closing them steam-tight; also having steam-pipe connections with a boiler, say F G H, and suitable stopcocks I for admitting steam supplied from any source; and shutting it oi, as required; for admitting it to either; or excluding it from the others; or allowing it to pass from one to another whileI stopping the supply from the boiler; the pipes F being liexible to allow the vessels to oscillatc.

cocks X for allowing the air to escape when the steam is admitted. These vessels I prefer to mount on a truck, K, of any kind, so that they may be moved readily along the street as the The said retorts will also have work progresses; and I propose to mount them on trunnions L, or to pivot them on a stand rising up from the truck-frame in any way, so that they may be tilted or oscillated forward or backward, as may be required for loading and dis* charging. For instance, when arranged as rep resented in Fig. 1, in which a platform, lVI, is placed above the vessels, on which to wheel'the gravel up for filling them, it will be necessary to tilt the vessels for discharging at one side of the truck; and when arranged as in Fig. 4, where-it is designed to maintain them in an oblique positionsay about forty-live degrees for filling and discharging-it is necessary to raise them up and maintain them in a horizontal position for moving from place to place. To hold them in the horizontal position I prefer to arrange them so that when in that position the lower sides will be sufficiently above the axles N to admit of inserting bars O under them and above the axles, which I propose to do to hold them as required. When arranging them in this way I propose to have doors P at each end, hinged, as shown, 'for swinging up on the upper side when opening, and to have the discharging end shaped obliquely, so that the door will be vertical or thereabout, and above the said lower door I propose to introduce a removable grate, Q, for maintaining a space, R, below it and above the door, in which the water which may form by condensation or collectV in any way may be separated from the gravel held above the grate. rlhe said grate will be maintained in position by legs S extending down and resting on the door. When arranged as in Fig. 4 a platform, T, will be maintained at one side of the truck in any suitable way to receive the gravel for convenience in lling. In this example the vessels are represented as connected together rigidly by bars or rods U, and they may have rigid pipe connections, which will otherwise be such as shown 'in Fig. l--that is,

steam to one, while shutting it of from the others, or to shut it o from all andallow the steam in use to escape to either of the others, as may be preferred. One of the vessels or retorts being filled with gravel, the cock admitting steam thereto will be turned and the steam let in, the air being allowed to escape, under such pressure as may be required to raise the gravel to a degree of heat considerably above that required for it when completed, and maintain it as long as reeu-ired, during which time another vessel may be filled; then thel cock admitting steam to the first will be closed, and another opened to allow the escape of the steam from the retort in which the operation is completed to the one newly filled, which takes and condenses it.-

Having thus described my invention, I claim as new and desire to secure by Letters 'PatentF l. The heating and drying of broken stone or gravel for roadways, pavements, sidewalks, roofing, or other purposes by the direct application of steam upon such stone or gravel, in a closed retort, at a temperature and pressure so much above that required for the stone or gravel when ready for use that, when the pressure is relieved and the steam allowed to escape, the water remaining upon the surfaces ofthe stone or gravel will be at once converted intosteam by the heat stored up in the mass, and the material left dry and at the temperature required, substantially as specified.

2. The utilization of the surplus heat by discharging the steam from a retort in which the heating has been completed into another retort similarly charged, substantially as described.

3. The combination and arrangement of retort-s substantially as described, for the purposes set forth.

CAMPBELL ALLEN.

Witnesses:

GEO. W. MABEE,

they will have the necessary cock to admit the T. B. Mosnnn. (110) 

